The invention relates to a method for monitoring a vibration gyro, which represents a resonator and is part of at least one control loop which excites the vibration gyro by supplying an excitation signal at its natural frequency, in which case an output signal can be tapped off from the vibration gyro, from which the excitation signal is derived by filtering and amplification.
By way of example, EP 0 461 761 B1 has disclosed rotation rate sensors in which a vibration gyro is stimulated on two axes which are aligned radially with respect to a main axis, for which purpose a primary and a secondary control loop are provided, with corresponding transducers, on the vibration gyro. When rotation rate sensors such as these are used in vehicles in order to stabilize the vehicle motion, dangers can occur as a result of failure or a malfunction. In order to prevent this, functional monitoring of the rotation rate sensor is required. This takes account of the fact that the vibration gyro is arranged in an evacuated housing in order to achieve the least possible damping, and that air can enter the housing as a result of ageing or a direct, reducing or precluding the usefulness of the vibration gyro.
In the case of JP 09-218040 A, monitoring such as this is carried our by the measuring the Q-factor of the resonator and by producing a fault message if the Q-factor is below a threshold value. In this case, the Q-factor is measured by switching off the excitation signal and by evaluating the amplitude of the the excitation signal in order to produce the fault message. The known method is essentially suitable for carrying out a test when the vehicle is stationary, for example in each case after switching on the ignition or during the checking of the rotation rate sensor during the course of manufacture.